U.S. Pat. No. 6,330,210 (Weirauch et al.) teaches a data structure (called a disk control block (DCB), on a rewriteable data storage medium, that among other things is used to control access for specific regions on the medium. For example, an access control block may divide a medium into regions, and the control block may specify for each region whether the drive has no access restrictions for the region, or whether the drive is permitted, in a region, to write, to format, to write-once, to read with password, to write with password, to format with password, to append with password, and so forth. Control blocks may be used for more than access control. U.S. Pat. No. 6,330,210 is hereby incorporated by reference for all that it teaches.
In general, a control block does not need to specify all control of regions at format time. New regions may be written, and a control block may be updated, or a new control block may be defined to specify control for the new regions. This creates two problems. First, performance may be reduced if a control block must be accessed and rewritten every time a new region is written. Second, for some types of rewriteable media, there is a limit on the number of times an area can be overwritten, and for some types of rewriteable media, repeatedly rewriting the same data in the same area can reduce the number of times the area can be rewritten. For example, for many types of data storage media, the smallest unit that can be read is commonly called a sector. For some media, each medium can hold on the order of 10 million sectors. If separate access control needs to be specified for each sector, the control block may need to be updated 10 million times if the medium is written completely. There is a need for improved control for data storage media.